Synthesis of linear and branched polyketones from the Rh complex catalyzed living alternating copolymerization of (4-alkylphenyl)allene with CO

Copolymerization of (4-hexylphenyl)allene and of (4-dodecylphenyl)allene with carbon monoxide (1 atm) catalyzed by Rh[eta(3)-CH(Ar')C{C(=(CHAr')CH2C (=C HAr')CH2CH2CH=CHAr'}CH2](PPh3)(2) (A; Ar' = C6H4OMe-p) gives the corresponding polyketones: I- [-CO-C(=CHAr)-CH2-](n) [1: Ar = C6H4C6H13-p, 2 :Ar = C6H4C12H25-p; I = CH2C(=CHAr')C(=CHAr')CH2C(=CHAr')CH2CH2CH=CHAr']. Molecular weights of the polyketone prepared from (4-hexylphenyl)allene and CO are similar to the calculated from the monomer to initiator ratios until the molecular weight reaches to 45,000, indicating the living polymerization. Melting points of the polyketones I-[-CO-C(=CHC6H4R-p)-CH2-], (n = ca. 100) increase in the order R = C12H25 < C6H13 < C4H9 < CH3 < H. Block and random copolymerization of phenylallene and (4-alkylphenyl)allene with carbon monoxide gives the new copolyketones. The polymerization of a mixture of (4-methylphenyl)allene and smaller amounts of bis(allenyl)benzene under CO afforded the polyketone with a crosslinked structure. (C) 2000 John WiIey & Sons, Inc. J Polym Sci A: Polym Chem 38: 1505-1511, 2000.